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NanoVNA are they any Good?

Discussion in 'Amateur Radio News' started by M1MRB, Feb 2, 2020.

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  1. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Update: I see that just recently BH5HNU, the creator of the F version, released several new firmware versions. I haven't tried them yet but from the descriptions they look good!
     
  2. KF5FEI

    KF5FEI Ham Member QRZ Page

    Local guy bought one to try tuning some cavities, and did a presentation about it recently. The gist of it was they are not a super-accurate piece of test equipment, compared to lab-grade stuff, but will suffice for most things. My take on like it was using a piece of string to find the center of a board, versus a tape measure with 100ths of an inch graduations. Both get you there, but one is more accurate.
     
  3. K5KTF

    K5KTF Ham Member QRZ Page

    Yeah, I have tried tuning my VHF WACOM cans, and have come up less-than-usable.
    I even tried narrowing the bandwidth/calibrating down to like 20KHz either side of each freq, tuned what showed to be good, but still getting bad desense.
    Now if someone could come up with a nanoSpectrum-Analyzer/Tracking-Gene for $50..... :)
     
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  4. KN4TRT

    KN4TRT Ham Member QRZ Page

    nanoVNA is GR8 especially using with the nanoVNA-Saver program. It is very easy to learn and it costs about $40.
     
  5. KU4PT

    KU4PT Ham Member QRZ Page


    Most likely problem is the nano does not have enough power output/receiver sensitivity to tune the notches. The notches will be below the ability of the nano. The same problem can be seen with some other SA/TG. My IFR 1200s has the same problem. However my HP 8924C works fine. YOu might try a preamp on the nano input or generate more power such as using a handytalkey on low power. You will probably need some 6 db or so attenuators to keep the impedance matched.
     
  6. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    The problem is the dynamic range is Of a Nano is only about 70 dB at best, which is fine for most amateur bench work. But a duplexer could easily require far more to show the notch properly.
     
  7. K5CO

    K5CO Ham Member QRZ Page

    How long does one have to listen to get to the subject of VNA's? I gave up with all the gaggle.
     
  8. W1MDM

    W1MDM XML Subscriber QRZ Page

    for 50bucks it is. it accurite, same reading with my RigExpert, live measurement and best for cavity filters. only negative is the small screen, get the larger one. its worth it.
     
  9. KQ6XA

    KQ6XA Ham Member QRZ Page

    I've found some of these toy analyzers (won't name names) are inadequate for use with antennas in urban or high-RF environments, such as near broadcast transmitters or repeater sites.
    The antenna picks up RF, and it can be stronger than the reflected power of the internal source.
    My experience is with using them about 1 mile away from a 25kW and 2 miles from a 50kW AM MW Broadcast site.
    To be fair, this is a common problem for many types of cheaper grade ham radio equipment (and some high-end gear as well).
    For filter work (duplexers, BPFs, LPFs, HPFs, notches, etc) where resistive terminations can be utilized on the test bench, RFI isn't a factor.
     
    Last edited: Feb 8, 2020
    N0TZU likes this.
  10. KM1H

    KM1H Ham Member QRZ Page

    If you mean the MFJ 259A/B, that has been a known issue since they came out in the late 80's. I have several 5-10KW AM stations LOS from this hill and could never get useful results on the 160 vertical, inverted V and the 5 2 wire Beverages.

    I wound up building a small 2 x 2N2222 VFO covering 1.5- 5 MHz and use the Oak Hills WM-2 QRP Wattmeter I built in the 80's and carry both to wherever I want including the top of a tower.

    So far the H and F nano VNA's havent left the house and there they exceed my expectations from LF to UHF; the F scanned the 160 and 80 TX antennas after sunset when the AM stations reduced power and all worked as expected. The Chinese update support is far better than MFJ ever was who constantly dropped support on older Revisions....lousy support IMO.

    The current project with the F is a USAF surplus BIG cavity amp that I will be trying to move up to 432 MHz and going to a friends machine shop once I get things figured out and with the F on hand can make incremental changes on site.

    Carl
     
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